Many special purpose tools are known in the art including flexible strap grippers for removing cylindrical oil filters. However specialty tools take up too much space or are expensive additions to a tool box particularly when used only occasionally. In general a pipe wrench and an oil filter removal wrench have been separate expensive and space hogging tools. On the other hand socket wrench systems are standard tool box items with attachments for reaching cramped working spaces and for providing extra leverage or ratcheting functions and the like.
For gripping and rotating cylindrical objects such as pipes and oil filters, special problems are posed. Metallic tools such as pliers and pipe wrenches are apt to scar and damage the exterior surfaces of the objects being gripped. Even more important, they cannot be used in cramped working quarters such as those about car engines, because of large size, long handles at the gripping site and the need for large turning arcs in order to produce high torque for initially breaking loose and then rotating in situ a cylindrical workpiece. Special tools employing a flexible strap for gripping and rotating cylindrical objects are described in U.S. Pat. Nos. 3,962,936, June 15, 1976, issued to W. H. Lewis and 4,221,140, Sept. 9, 1980, issued to B. B. Bracey, et al.
However, such prior art tools have several disadvantages. In each of these patents, for example, a separate specially designed accessory fitting is required for use only occasionally in the operation of the flexible strap.
Additionally, the functional operation of the flexible strap in gripping the cylindrical object is deficient, since it may slip or stretch unduly under high torque conditions. In practice the gripping strap is a fabric of the type that is used for seat belts and thus is subject to stretch. That is a significant disadvantage causing a very small working bite of the rotating leverage arm, particularly with a small diameter rod around which the strap is wound making the effective lever arm of the rotating member short. However, the small diameter is desirable for greater torque in initial unseating of an oil filter or pipe, and for taking up little storage space in a toolbox.
In these prior art tools, the effective working lever arm length of the rotating member is considerably decreased because of the combined strap slippage and stretch which accompanies the required wrapping of the strap material about the rotor lever rod used to exert the force on the strap for rotating in situ the cylindrical object, oil filter or the like.
Accordingly it is an object of this invention to provide simpler less costly tools of the aforesaid type that nevertheless correct the deficiencies of the prior art, take little storage space in a toolbox, have an extended range of utility and afford superior functional performance in the loosening and rotating of threaded cylindrical objects. Other objects features and advantages of the invention will be found throughout the following description, drawings and claims.